Integral 3-D foam core fabrics, composites made therefrom and methods of making

ABSTRACT

A 3-D woven fabric having substantially elongated foam elements integrally formed therein during fabric formation for providing open corridors within the fabric. The fabric is preferably used for structural, stiffener, or component applications.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is related to one or more co-pending USnon-provisional applications; it is a continuation-in-part of U.S.patent Ser. No. 10/716,959 filed Nov. 19, 2003, which was published asU.S. Patent Application Publication No. 2005/0146076 now abandoned,which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates generally to weaving and, moreparticularly, to 3-D woven fabrics, and composites made therefrom, andmethods of making same.

(2) Description of the Prior Art

Prior art cross-sectional shaped 3-D fabrics require looped selvageedges to secure the weft yarns during the fabric forming process, as setforth in U.S. Pat. No. 5,085,252 issued Feb. 4, 1992 to Mohamed et al.for a Method of forming variable cross-sectional shapedthree-dimensional fabrics. Prior art provides for laminating 3-D andother fabrics with foam to form “sandwich” or foam core fabrics;however, delamination problems exist whenever more than one layer isstratified without being permanently connected or integrated with thefoam layer.

Thus, there remains a need for a 3-D fabric having lightweight flexiblecore components integrally and unitarily formed with the fabric, whereinthe core components include foam elements.

SUMMARY OF THE INVENTION

The present invention is directed to a 3-D fabric having flexible corecomponents integrally and unitarily formed with the fabric, the flexiblecore components preferably formed from substantially elongate foamelements, which, if later removed form open channels, and methods ofmaking the fabric. The present invention also provides compositematerials formed from such fabrics.

These and other aspects of the present invention will become apparent tothose skilled in the art after a reading of the following description ofthe preferred embodiment when considered with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fabric body constructed according tothe present invention.

FIG. 2 is another perspective view of an alternative embodiment of thepresent invention.

FIG. 3 is another perspective view of an alternative embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, like reference characters designate likeor corresponding parts throughout the several views. Also in thefollowing description, it is to be understood that such terms as“forward,” “rearward,” “front,” “back,” “right,” “left,” “upwardly,”“downwardly,” and the like are words of convenience and are not to beconstrued as limiting terms.

Referring now to the drawings in general, the illustrations are for thepurpose of describing a preferred embodiment of the invention and arenot intended to limit the invention thereto.

The present invention provides an integral, unitarily formed 3-D foamcore fabric preferably using a 3-D woven fabrics having substantiallyelongated flexible elements or flexible core components included withinthe body of the fabric constructed and configured according to thepresent invention are preferably formed with substantially rectangularcross-sectional shapes and with a relatively thick z-directiondimension. In a preferred embodiment of the present invention theflexible core components are elongate foam elements. 3-D woven fabricsare known in the prior art, in particular being formed according tomethods set forth in U.S. Pat. No. 5,085,252 issued Feb. 4, 1992 toMohamed et al. for a Method of forming variable cross-sectional shapedthree-dimensional fabrics, which is incorporated herein by reference inits entirety.

As best seen in FIG. 1, a 3-D fabric is shown having three substantiallyorthogonal yarn component systems in x-, y-, and z-directions, with theflexible core components or elongate foam elements being introduced inthe y-direction or weft direction, preferably introduced during theweaving process. Alternatively, the foam elements may be introduced bysubstitution (FIG. 2) or attachment (FIG. 3).

The present invention provides for a 3-D woven fabric and methods ofmaking the same, the fabric having a plurality of orthogonal yarnsystems and corresponding yarn components thereof, including at leastthree directional systems: a warp, or x-direction; a weft, ory-direction; and a vertical or thickness corresponding to a z-direction,which are inserted into the fabric by reciprocation of a plurality ofharnesses that separate and directed movement of the z-direction yarnsby creating opposing groups for securing the warp and weft yarn systemsin place with respect to each other, the entire fabric and its pluralityof orthogonal yarn systems being secured at edges along the width of thefabric with respect to the fabric forming machine by selvage edgesformed by interplacing the weft yarns with selvage yarns whose movementis independently directed by corresponding harnesses to create at leasttwo opposing, compressive forces by selvage yarns against the thicknessof weft and warp yarns forming the fabric body along regions at thefabric edges. According to the present invention, the flexible corecomponents, which are preferably substantially elongate foam elementsare preferably inserted in the weft direction.

The harness components of a weaving machine for making the 3-D wovenfabric of the present invention are designed, constructed and positionedwithin the fabric forming machine for manipulating z-direction andselvage yarns such that the z-yarns form compressive forces against thecollection of warp and weft yarns of the fabric body, and providingsubstantially perfectly vertically stacked y-direction or weft yarns,thereby securing them in position with respect to each other.

The integrally, unitarily formed 3-D foam core fabric of the presentinvention having substantially elongated foam elements inserted in atleast one yarn component direction has a wide range of applications,including but not limited to structural composites, flooring, decking,vehicular and aircraft components, auto body parts, sporting goods andcomponents, stiffeners for all applications, furniture, in particularupholstery fabrics with padding, gaskets and seals, radiators and heatexchangers, and the like.

Referring now to FIGS. 1, 2 and 3, the present invention provides aflexible system/device material as shown in a 3-D woven fabric, whereinthe flexible material includes flexible core components or elongate foamelements that are introduced during the weaving process, as shown.Preferably, the flexible core components or elongate foam elements areused as one embodiment of the flexible elements set forth in the parentapplication, U.S. patent application Ser. No. 10/716,959, which isincorporated herein by reference in its entirety. Significantly, thefabric, which unitarily and integrally includes the flexible, elongatedfoam elements, forms both the skin and the core components that, in theprior art, are independently formed fabrics or layers that aresubsequently laminated or layered together. By contrast to the prior artskin/core materials, the present invention provides an integratedsandwich structure with a specific type of core formed integrally andunitarily formed as part of the fabric during 3D weaving process fromelongated foam elements. Thus, the present invention provides thecomplete sandwich structure, including both skin and core, with the foamcore being integral part of the fabric formed with the fabric as part ofthe fabric during the 3-D weaving process; it is during the fabricformation or weaving that the elongated foam elements are introduced,not later, as with prior art. The core portion of the sandwich is formedby the foam elements, which are inserted into the fabric duringformation, in the weft or y-direction.

In another embodiment of the present invention, a channel is formed onlyby the elimination of the foam elements from the core structure in asecond step or additional processing after formation of the fabricand/or composite material. Where elimination of the flexible or foamelements is desired to form a channel, the foam may be removed oreliminated to create channels in a secondary step. This is optional andis done in a later step, following the fabric formation or weavingprocess.

The flexible, elongate foam elements preferably range between very thin,threadlike in diameter, to as coarse as about one inch diameter orhigher. The only limitation is the shed space in the weaving process orinsertion space for other types of fabric formation, which may bemachine-dependent, or flexibility. Flexibility is important, inasmuch asit must be pulled through the opening for weft insertion; however, somestiffness may be acceptable, depending upon application of the fabric,so long as the capacity to introduce or manipulate the elements duringfabric formation is possible. Preferably, the foam elements arelightweight, such that the density is nearly zero. Thus, the weight ofthe structure is approximately the weight of the fabric itself, i.e.,the rest of the structure not including the foam elements. If a resin isinfused between the foam, such as between the z-yarns, then the resinweight is included in the composite structure weight. The foamessentially adds no weight to the fabric, i.e., the fabric weight issubstantially the same weight as the “skins” which is the rest of thefabric without the foam and/or the resin, which is added in the step ofcomposite formation.

The present invention includes a integrally, unitarily formed 3-Dmaterial further comprising foam elements that are substantiallyelongated foam elements, more preferably slender foam elements, that areinserted during fabric formation in a manner that is similar to otheryarn systems insertion. During the fabric formation, the elongated foamelements are inserted as a yarn component along with other yarns, orinstead of other yarns, depending upon the specifications and functionalrequirements for the fabric, as well as the strength and features of thespecific foam elements used.

These foam elements function to hold “open” corridors within the fabric,i.e., they provide lightweight channels within the fabric that may befurther processed, removed, or otherwise eliminated from the body of thefabric.

As with traditional 3-D fabric formation for “true 3-D” materials orstructures, the fabric is formed from a plurality of yarn systems thatare mechanically manipulated to interact with each other. 3-D fabrictypes appropriate for the present invention include weaving, knitting,braiding, stitching, interlacing, interlocking, and the like; in anycase, there is a requirement for modified equipment to manipulate thefoam elements for insertion or inclusion during the fabric formation. Bysignificant contrast to prior art foam core fabrics, the foam elementsof the present invention are inserted during fabric formation and areunitarily and integrally formed with the fabric, not laminated therewithor between more than one layer of fabric.

For the preferred embodiment of a 3-D woven fabric having substantiallyorthogonal structural elements, the fabric includes x-, y-, z-directionyarn systems to form a unitary, integral single ply fabric with nolamination. A particular end application for this embodiment is as aninsulating fabric within a structure. The fabric is flexible and/orcompliant following the weaving process, although its integral, unitaryformation eliminates delamination or separation of the foam elements,since they are part of the fabric structure itself, i.e., the yarncomponents include, are substituted, or are attached and replaced in atleast one direction by the foam elements.

In another embodiment, a multi-ply fabric is provided through asequencing fabric formation steps (by contrast to a single fabricformation in the case of a single ply fabric). One application formulti-ply 3-D fabrics having foam elements is as truss-like coredstructures. Once again, within any fabric layer there is no delaminationof the foam elements because they are integrally formed with the fabric.

Additional processing, such as, by way of example and not limitation,includes composites processing, surface treatments such as anti-skid, isoptional. Also, the fabric may be constructed so that the foam elementsprovide for foam surfaces on at least one side of fabric.

Certain modifications and improvements will occur to those skilled inthe art upon a reading of the foregoing description. By way of exampleand not limitation, the figures illustrate cross-sectional elementswhich are non-circular in cross-section; the present invention includescircular cross-sectional and/or non-circular cross-sectional elements,and combinations thereof. Also, in the figures, indication of flexiblesystem/device material are directed to the foam elements. Allmodifications and improvements have been deleted herein for the sake ofconciseness and readability but are properly within the scope of thefollowing claims.

1. A three-dimensional (3-D) woven fabric comprising: a 3-D woven fabricformed from three independent, orthogonal yarn systems and correspondingcomponents thereof, including a warp, x-direction components; a weft,y-direction components; and a vertical, thickness, z-directioncomponents; and selvage edges formed by the weft yarns and selvageyarns; wherein at least one of the yarn components includessubstantially elongate foam elements for providing lightweight foam corecomponents within the fabric with the elongate foam elements beingremoved or eliminated after fabric formation to leave open channelswithin the fabric.
 2. The fabric of claim 1, wherein the substantiallyelongate foam elements are inserted in the weft or y-direction.
 3. Thefabric of claim 1, wherein the substantially elongate foam elements areintroduced to replace yarns in the weft or y-direction.
 4. The fabric ofclaim 1, wherein the body of the fabric forms a substantiallyrectangular cross-sectional shape.
 5. The fabric of claim 1, wherein thesubstantially elongate foam elements are at least partially flexible. 6.The fabric of claim 4, wherein the open channels are filled with a resinto form a composite structure.
 7. The fabric of claim 1, wherein thefabric is treated with a resin to form a composite structure.
 8. Acomposite material comprising: a 3-D woven fabric formed from threeindependent, orthogonal yarn systems and corresponding componentsthereof, including a warp, x-direction components; a weft, y-directioncomponents; and a vertical, thickness, z-direction components; andselvage edges formed by the weft yarns and selvage yarns; wherein atleast one of the yarn components includes substantially elongate foamelements for providing lightweight foam core components within thefabric with the elongate foam elements being removed or eliminated afterfabric formation to leave open channels within the fabric; and whereinthe fabric is infused with a resin and cured to form a rigid compositestructure.
 9. The composite material of claim 8, wherein thesubstantially elongate foam elements are inserted in the weft ory-direction.
 10. The composite material of claim 8, wherein thesubstantially elongate foam elements are introduced to replace yarns inthe weft or y-direction.
 11. The composite material of claim 10, whereinthe fabric has a substantially rectangular cross-sectional shape. 12.The fabric of claim 8, wherein the substantially elongate foam elementsare at least partially flexible.
 13. The fabric of claim 8, wherein theopen channels are filled with resin during formation of the compositestructure.